mineral

Blue-green calcite/aragonite specimen

Likely calcite (CaCO₃), possibly aragonite; exact identification requires testing

AI-generated identification · may be incorrect

Pale blue-green to white, translucent, vitreous-to-pearly luster, and prominent cleavage/striations. Calcite has Mohs hardness 3, rhombohedral crystals, and strong effervescence in dilute hydrochloric acid; aragonite is harder (3.5–4) with orthorhombic structure.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms in carbonate-rich hydrothermal veins, caves, evaporite settings, and sedimentary environments; age depends on locality and may range from recent deposits to ancient Paleozoic or older rocks.

Uses & applications

Primarily a collector specimen; calcite is used for cement, lime, aggregate, and optical applications, while blue-green varieties are occasionally sold as decorative material.

Geological facts

The blue-green color commonly results from copper or other trace elements, though surface staining may also produce it. A streak and acid test help distinguish calcite from similarly colored minerals.

Field identification & locations

Common localities include Mexico, Peru, the United States, and China. Look for rhombohedral cleavage and acid reaction; avoid relying on color alone. Estimated value: $5–$30 for a small common specimen, or $50–$150+ if unusually vivid, crystalline, and well-formed.